Question

8: Answer to the following: a. Describe essential characteristics of the reversed Carnot refrigerator. b. Write down the formulas for the thermal efficiency of reversible heat engine and for the coefficient of performance (COP) of irreversible heat pump explicitly. Discuss the reason why the flow work of a heat pump must be minimized. d. Discuss which process is the best for a heat pump among the isentropic, polytropic, and isothermal processes in terms of the P-v property diagram.

Answer 1

temperature, Denise 6) sefbergeration effecting Ques8) a) The transfer of heat from lower temperature to a higher temperature requires a refrigerator It is work input device. Heat flows in the quiection of decreasing temperature. Desired effect With = 1-() Coppe=G-T c) To get higher value of (copy flow work - of heat pump must be minimized. - Tuote the difference between the first and second term ù larger than zero; and work input must be sufficiently big to make the sun to te equal to o. Thus there is a minimum work that is required for the machine that is heat pump to operate reversibly work input is obtained in process 3-4 Dsentropic process is best for a heat pump. CS Scanned with CamScanner